During the implantation of an endocardial lead, the lead is introduced into the heart using a venous approach, usually from the subclavian or cephalic vein in the shoulder area under the pectoral muscle. To keep the lead from shifting in the vein, the lead is secured to both the vein and to the underlying muscle tissue. A suture placed around the vein near the lead entry point ties the lead to the vein, and a suture sleeve around the lead is used to anchor the lead to adjacent tissue.
Suture sleeves in present use are generally tubular structures molded out of a soft, implantable elastomer such as silicone. After the lead is tied to the vein, the sleeve is slid along the lead to the location at which the lead is to be anchored to the underlying tissue. One or more sutures are then tied around the sleeve to compress it and thereby anchor it to the lead. Circumferential grooves in the outer surface of the sleeve are typically provided for this purpose. The last step is to anchor the sleeve to the body tissue; such anchoring is typically furnished by sutures passed through eyelets formed in a pair of tabs projecting from the sleeve.
Existing sleeves have several drawbacks. For example, only one lead can be secured within each suture sleeve. However, because many implants now use dual chamber pacemakers requiring at least two leads, this means that two or more sleeves must be secured to the surrounding tissue.
In addition, because most present suture sleeves are closed tubular structures that must be slid along the lead into position, sufficient flexibility must be provided to facilitate sliding the sleeve around curves in the lead. Furthermore, it is difficult for the physician to control the degree to which present sleeves are compressed when they are secured to a lead. The ligature around the sleeve must be tight enough to prevent the lead from sliding in the anchoring sleeve but not so tight as to damage the insulation of the lead. This is especially important with bipolar coaxial leads because an excessively tight ligature could rupture the lead insulation and cause the outer and inner electrical leads to come into contact with each other resulting in a short circuit.
Accordingly, it is an object of the present invention to provide a single suture sleeve for securely gripping and anchoring the leads of a multiple lead pacemaker.
It is another object of the present invention to permit positioning of the sleeve on the leads without having to slide it along the length of the leads.
It is a further object of the invention to provide a lead gripping and anchoring suture sleeve in which the compression of the sleeve is self-limiting so as to prevent lead damage.